1. Field of the Invention
The present invention relates to a power transmitting structure for a band saw and the transmitting structure comprises two shafts each having a plurality of gears mounted thereto and engaged with each other. A first shaft has an actuating rod slidably received therein and a slot defined in a peripheral wall thereof. The actuating rod has an engaging member optionally engaged with one of the gears to complete speed shifting without stopping the band saw.
2. Brief Description of the Prior Art
FIG. 1 shows a conventional band saw whose power transmitting structure generally comprising a bridge member 11 which has a first end having a motor 20 disposed thereto an a second end. The motor 20 has a first shaft 21 which has a first pulley 15 with a plurality of outer diameters. A second shaft 16 disposed parallel to the first shaft 21 has a second pulley 160 with a plurality of outer diameters. A belt 17 reeves through the two pulleys 15, 160. The second shaft 16 has a toothed end 161 which drives a gear 14 which is co-axially connected to a first wheel 13. The bridge member 11 has a second wheel (not shown) disposed thereto so that a band saw member 12 is rotatably connected between the two wheels. Therefore, the power from the motor 20 is transmitted to the two wheels 13 by the engagement of the gear 14 and the toothed end 161. However, the power transmitted by the belt 17 involves an inherent shortcoming which is that when a large torque is applied to the first pulley 15, a slide movement of the belt 17 may occur and such slide movement produces a large noise. Furthermore, when a different speed is required, the band saw must stop completely so as to shift the belt 17 to a different diameter of each pulley 15/160. This takes too much time and reduces working efficiency.
The present invention provides an improved power transmitting structure for a band saw so as to shift the speed of the band saw without stopping the band saw.